Insulin neuritis and diabetic cachectic neuropathy: a review

Diabetic patients can be affected by a wide range of peripheral nerve disorders, the rarer of which are often poorly recognised and understood. "Insulin neuritis" or "treatment induced neuropathy" is a reversible disorder characterised by acute severe distal limb pain, peripheral nerve fibre damage and autonomic dysfunction, preceded by a period of rapid glycaemic control. The condition has been reported in both type 1 and type 2 diabetics treated with insulin or oral hypoglycaemic agents who typically have a history of poor glycaemic control. Pathogenesis of the condition and its associated pain is poorly understood, with proposed mechanisms including endoneurial ischaemia, hypoglycaemic microvascular neuronal damage and regenerating nerve firing. Pain can affect other areas including the trunk and abdomen, or be more generalised. "Diabetic neuropathic cachexia" is a rare disorder associated with poor diabetic control that presents with large amounts of unintentional weight loss associated with an acute symmetrical painful peripheral neuropathy without weakness. Pain is characteristically burning in nature with predominant lower limb involvement and allodynia. The disorder can also affect type 1 and type 2 diabetics and occur irrespective of the duration of their diabetes. Depression and in males, impotence, appear to be common, although other autonomic features can be present. Typically it has a monophasic course but has been reported to be recurrent. As with insulin neuritis, this condition is reversible over weeks to months after adequate diabetic control. For both disorders, the pain can be treatment resistant despite the use of multiple analgesics.